The class attribute specifies a
classname for an element.
The class attribute is mostly used to
point to a class in a style sheet.
However, it can also be used by a
JavaScript (via the HTML DOM) to make
changes to HTML elements with a
specified class.
source
it's not poor form to use class attributes with no corresponding css rule...
it's even better to use class as a "data holder" than any other attributes like rel, title, etc...
